Sound-transmitter.



W. H. COTTON.

' SOUND'TRANSMITTBR.

APPLIQQTION FILED NOV.14, 1911.

Patented June 30,1914,

Wit 9 UNITED STATES PATENT OFFICE.

WALTER H. COTTON, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO S &. M ELECTRIC COMPANY, OF. CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKorA.

SOUND-TRANSMITTER lowing is a-full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

This invention relates to a novel device for amplifying the effects of sound waves impressed upon a diaphragm or like device, through the medium oflwhich diaphragm the efiects of said sound waves are transmitted to be reproduced as sound waves at a distant point.

My improvements are applicable, among other things, to the mouth piece of a telephone transmitter for amplifying the effect on the transmitter diaphragm of the vibratio-ns produced by the speaking voice.

The object of the invent-ion is to provide a simple and readily applied device of this character to transmitters for vocal or other sounds, which acts to concentrate and return the sound waves impressed upon the diaphragm or other transmitting medium and prevent the dissipation or loss thereof, to thereby increase the efficiency of the diaphragm or like medium to transmit sound Waves.

I have herein shownmy improvements as applied to telephone transmitters, in whichuseit enables the speaking voice to be car; ried greater distances, asfor long distance telephoning, and also permits lower tones, or whispering conversation, to be transmitted through the usual distances of local telephone service. My improvements are capable, however, of being employed in other devices for amplifying the effect of sound ,waves that are impressed upon a diaphragm at one point for electrical or mechanical transmission and reproduction at another point.

' The invention consists in the matters hereinafter described, and more particularly pointed out in the appended claims. I

In the drawings Figure l is a front elevation of one form of my invention applied to a telephone transmitter mouth piece.

Specification of Letters Patent.

stantially so.

Patented June 30, 19142.

Applicationfiled November 14, 1911. Serial No. 660,241

Fig; 2 is a section on the line 22 of Fig. 1. Fig. 3 is a front elevation of another form of the device. Fig. 4 is a section on the line it-4 of Fig. 3. Fig. 5 is a similar section showing a further modification. Fig. 6 is an inner side elevation of the sound amplifying device, removed from the mouth piece.

First referring to the construction shown in Figs. 1 and 2, 1O designates the ordinary bell shaped mouth piece of a telephone transmitter, the smaller open end of which faces the usual diaphragm 11, located in rear of the mouth piece and 12 the mouth piece support into which the mouth piece is screw-threaded in the-usual manner, said support being shown as provided with an annular flange 14: in which are formed the screw-threads to engage the screw-threads of the neck of the mouth piece. The diaphragm lland the parts associated therewith to transmit by its. vibrations sound waves impressed thereon may be arranged and supported in any suitable manner, depending upon the particular device in which it is found.

Located within the mouth piece and near its smaller rearwardly opening end is a hollow, concave reflector member 15 with its smaller end facing outwardly, and with its concave side facing inwardly. Said reilect-or member is supported concentrically in the mouth piece in any suitable manner so as to provide between the larger end thereof and the wall of the mouth piece a narrow annular'slit 16, through which the sound waves, projected into the larger end .of the mouth piece, pass rearwardly to the diaphragm 11 for impingement thereagainst to set up vib-rationsin the diaphragm by which the soundwaves are transmitted, either electrically or mechanically, from said transmitter. The internal diameter of the rear opening of the mouth piece is such, relatively to the external diameter of the reflector member, that the latter is substantially that of the former, so that substantially all the sound waves reflected by the member 15 pass in parallel lines of the diaphragm. The curved inner side of said reflector member is that of a parabola, or sub- The outer side of said member, or that facing the larger outer end of the mouth piece, is preferably of complemental configuration, thereby giving in effeet a pointed contour thereto, and provid- 7 ing an annular converging space about the deflector member which converges toward the slit 16. The sound waves such as are produced by speaking into the mouth piece, or otherwise, pass around said member 15 through the annular slit 16 and impinge or are impressed against the diaphragm 11.

The presence of the reflector member 15 in front of the diaphragm and between the same and the smaller part of the mouth piece has the effect to prevent the rebounding of the sound waves and the loss or dissipation thereof through the larger or open end of the mouth piece, the sound waves being intercepted by the curved inner side of the reflector device and reflected back against the diaphragm. By reason of the parabolic configuration of the inner surface of said device, the sound waves which strike same are'reflected back against the diaphragm in straight lines so as to thereby prevent the crossing or breaking up of the sound waves, and thus increase their effect on the diaphragm to set up vibrations therein and amplify the transmittingefi'ect 0f the transmitter. The said sound wave reflector member may be attached or fixed in the mouth piece in any suitable or preferred manner. As shown in Figs. 1 and 2, the said member is made integral with the wall of the mouth piece, it being provided with a plurality of arms 17 cast integral with the inner margin of said member and with the wall of the mouth piece.

As shown in Figs. 3 and 4, the sound wave reflector member 18 is made a part separate from the mouth piece and is adapted to be detachably fixed thereto, so that it may constitute an attachment for an ordinary mouth piece of a transmitter. For this purpose the reflector member is provided with a plurality of outwardly extending'arms 19, 19

which are formed at theirouter ends with hooks 20, 20 that are adapted to engage'over the outer margin of the enlarged end of the mouth piece. These hooks and arms are preferablymade of a material possessing some resiliency, so as to be automatically clamped in place when pressed into the mouth piece, and whereby the device may be readily removed, when desired. f

As shown in Figs. 5 and 6, the reflector member 22 is made a part separate from the mouth piece 10 and is flanged or provided with short arms 23, 23 adapted to be fitted into an annular groove formed in any suit-- able manner in the wall of the mouth piece in the inner, smaller end thereof, the annular grooved portion being spun or otherwise formed upon the ends of the arms 23 to hold the device in place. If desired the metal wall of the neck 25, on which is formed the screw-threads, may be turned inwardly or back upon itself and against the inner end of the reflector member 22, as shown in Fig. 5.

I claim as my invention l. A sound transmitter comprising a mouth piece, having a rearwardly opening end adapted to face a diaphragm at said rear end, a hollow reflector member arranged within the rear end of the mouth piece and having a parabolic surface facing said rear end, the inner end of said re- Hector member terminating short of the rear end of the mouth piece and being of a diameter at its rear end substantially that of the internal diameter of the rear end of the mouth piece, there being a sound passage at the" inner end of the reflector member through which sound waves pass around the inner end of said member to the diaphragm.

2. A sound transmitter comprising a mouthpiece having a rearwardly opening end adapted to facea diaphragm at the rear end thereof, a hollow reflector member arranged within the rear end of the mouth piece, and of an external diameter substantially that of the internal diameter of the rear end of the mouth piece, said mouth piece having at its rear end an externally screw-threaded cylindric attaching neck, the open rear end of the reflector member terminating at the smaller diameter of the'rear opening of said mouth piece, there being a passage for the sound waves between saidrear end of the deflector and said mouth piece, the inner rearwardly facing surface of the reflector member having a parabolic contour facing said diaphragm, and means to attach said member to the mouth -piece.

3. A month piece for a sound transmitter having a flaring open front end and having a smaller opening at its rear end adapted to face a diaphragm, and a hollow reflector member fixed within the rear end of the mouth piece with its curved side facing rcarwardly and with its rear end terminating short of the rear end of the mouth piece, and of an external diameter substantially that of the rear open end of the mouth piece, there being an opening at the inner end of the reflector member between the same and the rear part of the mouth piece for the passage of sound waves, and the interior surface of the reflector having a. parabolic ing formed at the rear end of member and between the same and the smaller end of the mouth piece a passage for sound waves and a radially extending part at the rear end of the reflector member to enter a groove or recess in the mouth piece totherebyattach the reflector member to the mouth piece.

5. A sound transmitter comprising an. outwardly flaring mouth piece, a diaphragm in rear thereof and a concavo-convex reflector within and at the smaller end of the mouth piece which is formed at itsinner side with a parabolic surface which faces the diaphragm, there being formed around said member and between the same and the smaller end of the mouth piece an.

annular space for the passa e of the 'sound waves to the diaphragm, t e wall of the mouth piece being provided with, an annular groove and the inner margin of the re flector member being provided with arms which enter said groove and are confined therein.

- 6. A flaring mouth iece for a ransmit ter provided at its 'u ner end within the same with a concavo-convex reflector member the concave side of which faces inwardl said member being provided at its inner si c with arms and thewall of the mouth piece havinga firooved portion into which said arms t an which 1s spam or formed on said arms to hold said mem er in place.

In testimony, that I claim the foregoing as my invention I afiix my signature in the resence of two witnesses, thls 9th day of ovember, A. D. 1911.

. WALTER H. COTTON.

Witnesses: 1

G. E; Downs, --Wn.nmu Gonmsnnenn. 

